1. Field of the Invention
The present invention relates to an electrographic photoconductor and an image forming apparatus having the electrographic photoconductor.
2. Description of Related Art
Electrophotographic image forming apparatuses use an electrographic photoconductor (which may hereinafter be simply referred to as “photoconductor”) to form an electrostatic latent image to be developed into an image to be formed. Such an electrophotographic image forming apparatus first applies light to the charged photoconductor to form the electrostatic latent image. Next, the apparatus feeds a toner to the photoconductor to form a toner image based on the electrostatic latent image. The apparatus finally fixes the toner image onto a recording medium such as paper.
Known examples of the technique used in electrophotography to charge a photoconductor include a contact type charging technique using a charging roller or charging brush (this technique may hereinafter be simply referred to as “roller charging system etc.”) and a non-contact type charging technique using a wire or the like (this technique may hereinafter be simply referred to as “scorotron charging system”). The roller charging system etc. make use of nearby discharge and cause a greater deterioration of the surface of the photoconductor at the charging than the scorotron charging system. In the roller charging system etc., high-energy charged objects such as electrons resulting from nearby discharge collide with the surface of the photoconductor to charge the photoconductor. At this charging, discharge of the photoconductor penetrates in the direction in which the layers of the photoconductor are stacked, thereby deteriorating the photoconductor. To address such deterioration of photoconductors, photoconductors have been known which contain a layered compound added to physically block the penetration of discharge (see Japanese Patent Application Laid-Open No. 2007-064998 and Japanese Patent Application Laid-Open No. 2014-142571, for example).
The photoconductor described in Japanese Patent Application Laid-Open No. 2007-064998 has a conductive layer, a charge generation layer disposed on the conductive layer, a charge transport layer disposed on the charge generation layer, and a protective layer disposed on the charge transport layer. The photoconductor contains a thermosetting or thermoplastic resin and a flat inorganic filler. The flat inorganic filler is a layered clay compound such as smectite, mica, or vermiculite.
The photoconductor described in Patent Application Laid-Open No. 2014-142571 has a support, a photosensitive layer disposed on the support, and a surface layer disposed on the photosensitive layer. The surface layer contains: an organic-inorganic hybrid material containing an inorganic component and an organic polymer; and a clay mineral. The clay mineral is montmorillonite, hectorite, vermiculite, attapulgite, sepiolite, or the like.
The photoconductors described in Japanese Patent Application Laid-Open No. 2007-064998 and Japanese Patent Application Laid-Open No. 2014-142571 may fail to sufficiently block the penetration of discharge, due to narrow spread of the flat inorganic filler or clay mineral in the surface layer.